There are 25% more yellow stickers than grey stickers in a bag. After Mark removed 20% of the yellow stickers and increased the number of grey stickers by 30%, there are now 24 fewer yellow stickers than grey stickers. Find the number of grey stickers at first.

	Yellow	Grey
Before	5 u	4 u
Change	- 1 u	+ 1.2 u
After	4 u	5.2 u

Number of yellow stickers in percentage
= 100% + 25%
= 125%

125% = ¹²⁵₁₀₀ = ⁵₄

Number of yellow stickers that Mark removed
= 20% x 5 u
= ²⁰₁₀₀ x 5 u 
= 1 u

Number of grey stickers that Mark increased 
= 30% x 4 u
= ³⁰₁₀₀  x 4 u
= 1.2 u

Number of yellow stickers in the end
= 5 u - 1 u
= 4 u

Number of grey stickers in the end
= 4 u + 1.2 u
= 5.2 u

Number of fewer yellow stickers than grey stickers in the end
= 5.2 u - 4 u 
= 1.2 u 

1.2 u = 24

1 u = 24 ÷ 1.2 = 20

Number of grey stickers at first
= 4 u
= 4 x 20
= 80

Answer(s): 80